The Effect of Different Pretreatment on Mitosis

The effect of different pretreatment on mitosis of onion root tip was studied. The results showed that among the four pretreatments, the 0.2% colchicines pretreatment could increase the mitotic index vitally apparently, which was 3. 2 times of that of the control; the low-temperature pretreatment could also increase the mitotic index by 1.57 times, and it is also the primary choice in most of the teaching experiments.